Method for imparting antistantic properties to textile materials



United States Patent 3,353,993 METHOD FOR IMPARTING ANTlSTATICPROPERTIES TO TEXTILE MATERIALS Tokurou Kida, Otokuni-gun, Kyoto, ShougoMatsuda and Seiichi Saito, Takatsuki-shi, Osaka, and Masaharu Yuasa,Nakagyo-ku, Kyoto, Japan, assignors to Asahi Chemical Industry Co. Ltd.and Tauabe Seiyaku Co.

Ltd., Osaka, Japan No Drawing. Filed Apr. 28, 1964, Ser. No. 363,295

Claims. (Cl. 117139.5)

ABSTRACT OF THE DISCLOSURE An antistatic treatment for synthetic fibersusing as an antistatic agent aliphatic and aromatic aspartates,glutamates and their N-alkyl or acyl derivatives and alkyl 2-pyrrolidone 5 carboxylate; and a product thereof.

This invention relates to a method for imparting antistatic propertiesto textile materials.

Many textile materials display a tendency to collect static chargesduring their manufacturing operations. Garments made therefrom alsocollect static charges by rubbing. This tendency presents a particulardifficulty in the case of synthetic fibers to the point that they cannotbe handled without using some antistatic agents, and garments madetherefrom can be seriously hazardous unless some antistatic agents areused. The generation of high static charges causes the fibers to flyapart, owing to mutual repulsion, and to adhere to any uncharged oroppositely charged object. This leads to many difficulties, such asdecrease of operativeness, electrical shocks, spark discharges and thelike. In case of garments made therefrom, static charges cause toattract dust and soil, and to give uncomfortable shocks and sparks tothe wearer especially when removing the garments.

It has previously been known that textile materials can be preventedfrom acquiring high electric charges by allowing them to leak away in aphysical manner or by applying an antistatic agent to the textilematerials. Various types of such antistatic agents are known. Many ofthem depend on reducing the electric resistance of the textile materialsso they impart antistatic properties to textile materials which tend tocollect such charges. These agents must be physiologically harmless tothe wearers and have no undesirable affect on the physical properties ofthe materials themselves. During their manufacturing operations, it isrequired that such agents can be employed in standard manufacturingpractice with no special precautions or fear of corrosion to theequipment. It is almost impossible to satisfy all of the above mentionedrequirements with any of the commercially available antistatic agents.

According to this invention, We have found that antistatic propertiesmay be imparted to textile materials by applying thereto alphaaminocarboxylic acid derivatives represented by the formulae:

R 0 0 C (CHQHCHCOOR wherein R and R represent hydrogen, aliphatic oraromatic hydrocarbon groups except both do not represent hydrogensimultaneously, R and R represent hydrogen, alkyl or acyl groups, Rrepresents aliphatic or aromatic hydrocarbon radicals, and n representsan integer of 1 or 2.

Illustrative examples of' above-mentioned compounds are, diethylaspartate, di-n-butyl aspartate, di-n-octyl aspartate,di-(2-ethyl-hexyl) aspartate, di-n-butyl N-acetylaspartate,di-(Z-ethylhexyl) N-acetylaspartate, dimethyl N-benzoylaspartate,di-n-butyl N-benzoyl-aspartate, dimethyl N-ethoxycarbonylaspartate,di-n-butyl N-ethoxycarbonylaspartate, diethyl, N,N-dimethylaspartate,di-nbutyl N,N-dimethylaspartate, di-(Z-ethylhexyl)N,N-dimethylaspartate, beta-n-butyl aspartate, beta-benzyl aspartate,beta-benzyl N-benzoylaspartate, diethyl glutamate, di-n-butyl glutamate,d-(Z-ethylhexyl) glutamate, di-n-butyl N-acetylglutarnate,di-(Z-ethylhexyl) N-acetyl glutamate, di-n-butyl N,N-dimethylglutamate,di-QZ-ethylhexyl) N,N dimethylglutamate, ethyl 2 pyrrolidone-S-car-boxylate, n-butyl 2-pyrrolidone-5-carboxylate, n-octylZ-pyrrolidone-S-carboxylate and 2-ethylhexyl2-pyrrolidone-S-carboxylate.

They may be used in any optically active or inactive forms in practicingthe present invention. Most of them are relatively stable on heating andin Water or organic solvents. Although they are generally insoluble inwater, they may be dissolved or dispersed in water by heating or addingsurface active agents such as polyoxyethylene alkyl ether or those knownas Tween and Span. Such surface active agents may be satisfactorilyemployed to-dissolve active ingredients without fear of loss ofantistatic properties thereof. They are also soluble in many alcoholssuch as methanol, ethanol or'propanol and so alcoholic solutions thereofcan be easily prepared.

The mixtures for use in carrying out the present invention preferablycontain from about 0.05 to 5% by weight per volume of one of suchcompounds therein. They may be prepared by dissolving or uniformlydispersing the active ingredients in water or an organic solvent. Thetreating mixtures can be applied to textile materials which display atendency to acquire static charges in any conventional manner. The usualpadding, dipping or spraying techniques can be used on fibers, yarns,fabrics and the like. They may be, if desired, rendered insoluble oraflixed to the materials whereby they become fast to both washing anddry cleaning. This can be performed, for instance, by treating withresins such as polyacrylic ester, trimethylol melamine, guanidinephosphate-formaldehyde and epoxy resins. It is also possible toincorporate some known antistatic agents for use in the treatment of theinvention.

After applying the mixture, the textile materials are squeezed to removeexcess liquid and then dried or cured in any conventional manner. Thecompounds used in the present invention have many advantages for use intextile materials as an antistatic agent. They do not blemish textilematerials, even upon radiation of light and heating at -a temperaturebelow the softening point of the fiber.

They are almost harmless to the human body. As a result of toxicity testusing mice, they showed LD of more than 10 mL/kg. by oral administrationand 5 ml./ kg. by intraperitoneal administration. They did not show anyirritating properties to skins when pure compounds and 25% solutionswere applied on the neck of male rabbits. As to the effect on touch ofthe fabrics which is very important, almost no change can be seenbetween treated and untreated fabrics.

According to the invention, static charges on the fabrics can be reducedto practically negligible amounts for use in garments. The treatment ofthis invention can also be practiced on the textile materials duringtheir manufacturing operations to avoid many hazards caused by staticcharges.

As a test of the effectiveness of the treatment, both the electricresistance and static potential of the material were measured, thelatter immediately after rubbing. It has been known that the tendency toaccumulate static charges may be determined by measuring the resistanceof the article to be tested. It has also been known that garments arealmost non-susceptible to static charges upon wearing or generatedstatic charges can leak away therefrom if they show a resistance lessthan ohm/cm. But the resistance alone is not always identical to thetendency to generate static charges upon rubbing, so we have carried outthe following tests.

The fabric under test is set on a cylinder having a diameter of cm. Thecylinder is rotated at 700 r.p.m. As the cylinder rotates, the fabricrubs against a surface of leather. The fabric is rubbed for five minutesand the potential built up thereupon is measured with an electrometerimmediately. After allowing to stand for one minute, the residualpotential is also measured. According to this test, a standard cottonfabric shows an initial potential of 0.3 kv. and a residual potential ofalmost zero level. Since cotton fiber has been considered to benon-susceptible to static charges, it can be considered that theantistatic treatment is successful if the result obtained shows a degreealmost the same as cotton fabric. Typical results obtained from the teston some untreated fabrics are shown in the following table.

TABLE I. (45% R.H. at 30 C.)

Initial potential Residual Fabric Resistance after potential (ohm/cm.)rubbing (kilovolt,

(kilovolt, 1 minute) 5 minutes) Acrylic 10 1. 1 0. 6 Polypropylene 10 2.2 2. 0 Nylon 10 1. 2 0. 4 Polyester 10 0.3 0. 2

The invention will be illustrated by the following specific examples inwhich all are parts by weight unless otherwise indicated. The results ofeach of the following are found in Table II.

Example 1 4 Example 2 Nylon taffeta fabric was treated with a bathcontaining 2% by weight per volume of di-n-butyl L-aspartate in methanolas in Example 1.

Example 3 Di-n-butyl N-acetyl-L-aspartate was prepared by mixing partsof dim-butyl L-arpartate, 42 parts of acetic anhydride and 33 parts ofpyridine, allowing to stand to complete the reaction and distilling thereaction mixture. A mixture of 5 parts of di-n-butylN-acetyl-L-aspart-ate and 1 part of polyoxyethylene oleyl ether washeated at about 60 C.

To the mixture was added an amount of hot water at the same temperaturewith stirring until the concentration reaches to 30% by weight pervolume and then cooled. The resulting mixture was diluted with coldwater to the concentration of 0.5% by weight per volume. Nylon fabricwas treated with the diluted mixture as in Example 1.

Example 4 A fabric made of acrylic spun yarn was treated with a bathcontaining 0.5% by weight per volume of di-nbutyl N-acetyl-L-aspartatein methanol as in Example 1.

Example 5 An aqueous emulsion containing 0.5% by weight per volume ofdi-n-butyl N-acetyl-L-aspartate and 0.1% by weight per volume ofpolyoxyethylene oleyl ether was prepared. An acrylic fabric was treatedwith the emulsion as in Example 1.

Example 6 Di-n-octyl L-aspartate was prepared by reacting 10 parts ofL-aspartic acid with 75 parts of n-oct-anol as in Example 1. A nylonfabric was treated with a bath containing 0.5% by weight per volume ofdi-n-octyl L-aspartate as in Example 1.

Example 7 Di-n-butyl D-glutamate was prepared by saturating a mixture of5 parts of D-glutamic acid and 30 parts of nbutanol with hydrogenchloride gas and heating the mixture. 23 parts of said ester, 9 parts ofacetic anhydride and 7 parts of pyridine were mixed, allowed to stand tocomplete the reaction and then distilled, whereby di-nbutylN-acetyl-D-glutamate was obtained. A fabric made of polypropylene fiberwas treated with a bath containing 0.5 by weight per volume ofdi-n-butyl N-acetyl-D- glutamate in methanol as in Example 1.

Example 8 0.9 part of polyoxyethylene oleyl ether, 0.1 part ofpolyoxyethylene sorbitan mono-oleate and 5 parts of di-n-butylN-acetyl-D-glutamate were heated at about 60 C. To the mixture was addedan amount of water of the same temperature with stirring until theconcentration reaches to about 30% by weight per volume and cooled. Theresulting mixture was diluted to the concentration of 2% by weight pervolume with cold water. A polypropylene fabric was treated with themixture as in Example 1.

Example 9 An aqueous emulsion containing 0.5% by weight per volume ofdi-n-butyl N-acetyl-D-glutamate and 0.1% by weight per volume ofpoly-oxyethylene oleyl ether was prepared. A polyester fabric wastreated with the emulsion as in Example 1.

Example Example 11 Di-(2-ethylhexyl) N-acetyl-D-glutamate was preparedby mixing 50 parts of di-(2-ethylhexyl) D-glutamate, 14 parts of aceticanhydride and 11 parts of pyridine, allowing to stand to complete thereaction and distilling. 0.9 part of polyoxyethylene oleyl ether, 0.1part of polyoxyethylene so'rbitan mo'no-oleate and 5 parts ofdi-(Z-ethylhexyl) N-acetyl-D-glutamate were heated at a temperature ofabout 60 C. to about 70 C.

To the mixture was added an amount of water of the same temperature withstirring until the concentration reaches to about 40% by weight pervolume and then cooled. The resulting mixture was diluted to theconcentration of 2% by weight per volume with cold water. A nylon fabricwas treated with the mixture as in Example 1.

Example 12 An aqueous emulsion containing 2% by weight per volume ofdi-(Z-ethylhexyl) N-acetyl-D-glutamate and 0.4% by Weight per volume ofpolyoxyethylene oleyl ether was prepared. A polypropylene fabric wastreated with the emulsion as in Example 1.

Example 13 An acrylic fabric was treated with 0.5% by weight per volumesolution of n-butyl 2-pyrrolidone-5-carboxyl'ate in methanol as inExample 1. The same treatment was repeated using polypropylene fabricand 2% by weight per volume aqueous solution of said compound. Apolyester fabric was also treated with 0.5% by weight per volume aqueoussolution of the same compound.

Example 14 An acrylic fabric was treated with 0.5% by weight per volumesolution of Z-ethylhexyl 2-pyrrolidone-5-carboxylate in methanol as inExample 1.

Example 15 A 5% by weight per volume aqueous solution of nbutyl2-pyrrolidone-5-carboxylate was sprayed to an acrylic fabric to give apick up of 15% based on the weight of the fabric and then dried.

Example 16- 3 parts of di-n-butyl N-acetyl-D-glut-amate was added to 100parts of aqueous solution of polyacrylic ester resin, and 1 part oftrimethylolmelamine and 0.2 part of Z-imino-iso-propanol hydrochloridewere added to the mixture.

A polyester fabric preliminarily dried at 70 C. for 2 minutes was paddedthrough the resulting mixture as in Example 1 and cured at 140 C. for 5minutes. The resultant fabric showed an excellent antistatic property.

Example 17 2 parts of di-n-butyl N-acetyl-D-glutamate was added to 100parts of 2.6% aqueous solution of guanidinephosphate-formaldehyde resin,and 1 part of trimethylolmelamine was added to the mixture. Example 16was repeated with an acrylic fabric using the resulting mixture. Theresultant fabric showed an excellent antistatic property.

TABLE II Initial potential Residual Example Resistance alter potential(ohm/em.) rubbing (kilovolt, (kilovolt, 1 minute) 5 minutes) 1 See TableIII for Example 13.

TABLE III Example 13 Initial potential Residual Fabric Resistance afterpotential (ohm/cm.) rubbing (kilovolt, (kilovolt, 1 minute) 5 minutes)Polypropylene 1X10 0. 08 0. 02 Acrylic 2X10 0. 06 0 Polyester 3X10 0.003 0 We claim: 1. Method for imparting antistatic properties to textilematerials made of synthetic fibers whch comprises applying to saidmaterials, as an antistatic agent, a compound selected from the groupconsisting of:

R 0 0 C (0112),; OHCOOR ing of hydrogen and a hydrocarbon radical exceptthat both are not hydrogen simultaneously, R and R are selected from thegroup consisting of hydrogen, an alkyl and an acyl radical, R is analiphatic hydrocarbon radical and n represents an integer of 1 and 2,and drying said materials.

2. The method in accordance with claim 1, wherein said compound isapplied together with a water soluble resin whereby said compound isdeposited on the material to form a durable antistatic finish.

3. The method in accordance with claim 1, wherein said compound isapplied to the textile materials during their manufacturing operations.

4. A method according to claim 1 wherein said R and R are C H R isacetyl, R is hydrogen, and n is 2.

5. Textile materials made of synthetic fibers having an antistaticcoating thereon comprising a compound selected from the group consistingof:

R oo0-(cH2 n0H00oR and Wherein R and R are selectedfrom the groupconsisting of hydrogen, alkyl radical and benzyl radical except thatboth are hydrogen not simultaneously, R and R are selected from thegroup consisting of hydrogen, an alkyl and acyl radical, R is selectedfrom the group consisting of an alkyl radical, and n is an integer of 1and 2.

References Cited UNITED STATES PATENTS 3,212,927 10/1965 Williams117-1395 X FOREIGN PATENTS 483,224 4/1938 Great Britain.

WILLIAM D. MARTIN, Primary Examiner.

T. G. DAVIS, Assistant Examiner.

1. METHOD FOR IMPARTING ANTISTATIC PROPERTIES TO TEXTILE MATERIALS MADEOF SYNTHETIC FIBERS WHICH COMPRISES APPLYING TO SAID MATERIALS, AS ANANTISTATIC AGENT, A COMPOUND SELECTED FROM THE GROUP CONSISTING OF: